Ph.D. Thesis Proposal by
(Advisor: Prof. Suresh Menon)
“A Numerical Study of Super-Critical Reacting Flows with Vapor-Liquid Equilibrium (VLE)”
November 13, 2017 @ 4 p.m.
Montgomery Knight Building, Room 317
Increase of the operating pressure in combustion systems can achieve better combustion efficiency and propulsive performances. This characteristic is shared among different types of applications, ranging from diesel engines to gas turbines to liquid rocket engines (LRE). Particularly, in LRE, propellants are stored in their liquid state at high pressures but at temperatures lower than their critical values resulting in thermodynamic conditions that range from the “super-critical” regime (injection/mixing), to the “ideal gas” regime (complete combustion/nozzle expansion). Strong differences have been observed between jets at sub- and super-critical pressures, indicating that deviations in thermo-physical properties from their ideal state are extremely important and need to be accurately modeled. However, while thermodynamic models for single species are well established, correct representation of multi-component mixtures is still not well understood. This becomes an important requirement for high-fidelity simulations that aim to predict LRE conditions since early phase of propellants injection and mixing in the combustion chamber is critical for performance assessment.
In this work, the challenges associated with the thermodynamic modeling of multi-component mixtures at super-critical conditions are addressed in the context of high-fidelity simulations. It is shown that the single-fluid approach that uses a single equation of state (EoS) to model the thermodynamic properties may fail in multi-component fluids because an additional phase information is missing. This information is included by using the Vapor-Liquid Equilibrium (VLE) concept and it is shown that consistency with thermodynamic properties is obtained for a range of multi-component mixtures. The ability of VLE combined with real-gas EoS to handle mixed regimes will be assessed using large-eddy simulations (LES) of canonical reacting shear layers as well as LRE type high-pressure reacting configurations (e.g., shear coaxial injectors).